Contact device



Dec.'l5, 1970 G, BERGSON i 3,546,929

` 1 CONTACT DEVICE Filed Aug. 22, 1969 INVENTOR. USIGI/ ergson United States Patent() 3,546,929 CONTACT DEVICE Gustan Bergson, Cedarbrook Hill Apt. 2, B-117,

' Wyncote, Pa. 19095 Filed Aug. 22, 1969, Ser. No. 853,234 Int. Cl. G01n 1/28; G0111 5/28 U.S. Cl. 73--78 2 Claims ABSTRACT F 'THE DISCLOSURE A device for determining when a cutting tool is in contact with a surface consisting of a pivoted rod with a tool holding structure thereon whereby pivotal motion can only occur when the cutting tool is not in contact with the surface. A displacement indicator engages the rod at the end opposite the pivot point to detect pivotal motion.

SUMMARY The invention presents a means for determining a condition of initial contact between a tool and a surface wherein essentially zero force exists. The Icondition is capable of determination within better than 0.0001 While the construction is suiciently rugged to permit forces appropriate to extend applications.

It is desirable to have a means of precisely determining a condition in which contact is just made between a rigid surface and an edge which may be part of a cutting tool. Thus it is sometimes desired to iix this point as the condition of zero force between the edge and the surface, in mutual contact, as a preliminary to the study of a surface hardness characteristic of material which may be a nonconductor of electricity, said material being placed between the surface and the tool. In this case, the zero force contact point, to be determined, becomes that between the inserted material and the tool.

The present invention gives a means of doing this wherein an economic indicator is used in a fashion to permit a displacement of less than1l000l from mutual contact to be easily observed, whilethe determination of the contact point does not require any delicacy of handling such as might be expected in such usage.

The system is capable of rugged use with no damage to the sensitive indicator. It will be better understood with reference to the `figures while taking account of the fact that the principles of the invention are intended to include obvious variation.

FIG. 1 is a schematic elevation according to the preferred embodiment of the invention;

FIG. 2 is a schematic side elevation partially in section showing the screw mechanism.

In FIG. 1 there is shown a rigid plate 4 which mounts a support 3 for a pivot point 1 |which is bearing mounted in 3 for minimum friction. The rod 2, rectangular in this usage, is mounted olf of 1 in a fashion to permit its small angular rotation around the pivot point. The frame 5 is mounted on 2 by the screws 21 and 22 and 5 permits insertion of a tool 20 through a hole at 6, this tool being held in position with respect to the frame by a collar 9 which is attached to the tool by screw 10. The collar 9 consists of a rectangular plate extending beyond screw 11, (FIG. 2), while a clearance hole through 9 permits free passage of 11 through it. The head 13 of 11 maintains contact with the upper surface of 9 while the spring 8 pushes between the frame and 9 to insure this contact, this spring being around the upper portion of the tool 20 3,546,929 Patented Dec. 15, 1970 ice as shown in FIGS. 1 and 2. Screw 11 drives up or down in the frame 5 as shown. in FIG. 2.

At one end of the rigid plate 4 there is mounted a support 16 for a displacement indicator 17 whose linger 18 contacts the upper edge of the rod 2 at the end remote from the pivot point. The rod 2 has a slot 25 into which the rod 19, mounted on 16, can be inserted, and this slot is dimensioned to permit a loose fit of 19 in it.

On the other end of 2 there is inserted a threaded rod 15 on to which a weight 14 is mounted in a fashion to permit balancing all of the xed members to the right of the pivot point by the positioning of 14. In practice this balance is obtained with rod 19 contacting 2 in the upper portion of slot 2S at 26.

In this initial balanced position the tool 20 is up away from the surface of 4, or any material on it, and the point of contact is obtained by intermittent turning of the head 13 of 11, FIG. 2, to advance the tool toward the surface to be contacted. Following each turn of 13, a slight pressure is applied at the point 24 on its top and each pressure causes a significant deflection of the indicator 17, due to transmission through frame 5 to rod 2. However, at the point where contact is made there is no longer any displacement transmitted to 17 and no displacement appears on the indicator. The head 13 can be backed olf slightly to again obtain a displacement by pressing at 24 and then turned to the very sharply discernible point of the start of no displacement. This is the desired point.

I have used an indicator with divisions at every 0.0005 and a standard thread screw of 18 threads per inch whereby it is readily possible to adjust the wide knurled head 13 to .better than 0.0001 on the indicator iinger 18. Since the indicator is located farther from the pivot point than the frame 5, the observed displacement is greater than that at the contact point of interest.

What is claimed is:

1. In combination, a pivot point, a rod capable of angular motion with respect to said pivot point, a means whereby said pivot point is held in fixed vertical location with respect to a rigid plate, a frame mounted in a fixed position on said rod, a means for mounting a tool in said frame, a means for adjusting the position of said tool with respect to said frame, said adjustment being toward or away from said rigid plate by the turning of a screw, a means for balancing said rod, frame and tool about said pivot point, an indicator mounted on said rigid plate, said indicator having a displacement measuring finger contacting said rod near the end thereof whereby displacement of said rod about said pivot point is indicated.

2. The combination set forth in claim 1 and including a slot in the end of said rod into which a second rod can be loosely projected, said second rod being mounted on the indicator mounting.

References Cited UNITED STATES PATENTS 2,624,948 1/1953 Kemph 33-148 2,938,377 5/1960 Sklar 73-83 3,345,753 10/ 1967 Giardino 33-148X RICHARD C. QUEISSER, Primary Examiner E. I. KOCH, Assistant Examiner U.S. Cl. X.R. 73-105 

